Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

921
FXUS63 KLOT 230609
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
109 AM CDT Sat May 23 2026

.KEY MESSAGES...

- Scattered showers generally along/east of I-57 tonight.

- Chance of showers and isolated thunderstorms Saturday evening
  through midday Sunday.

- Above normal temperatures expected early next week.

&&

.DISCUSSION...
Issued at 225 PM CDT Fri May 22 2026

Current temps are likely the highs for today, lower 70s well
inland with some sunshine earlier and then 60s for much of the
metro area and 50s near the lake. Cloud cover will increase this
afternoon as low pressure lifts north across Indiana overnight
and into southeast Michigan Saturday. There will likely be a
rather sharp gradient to the showers on the west side of this
system. Areas west of I-57 will be mainly dry with a period of
rain expected for northwest Indiana overnight/early Saturday
morning. There will be a low chance (20-30%) for showers for
Cook and Lake County Illinois during the overnight hours, but
most areas will remain dry. There may be a few lingering showers
after daybreak near and over Lake Michigan. While an isolated
thunderstorm is possible tonight, mainly east of the local area,
chances are low and have no thunder mention tonight.

A lull in the precip chances is expected from late morning
through mid afternoon Saturday, then a weak cold front and upper
trough will approach the area by early evening with at least a
slight chance (20%) of showers into the evening hours. There is
some weak instability by early evening and if any showers are
able to develop, then isolated thunder will be possible and
opted to include slight chance thunder Saturday evening. It
appears whatever develops may try to fade by mid/late evening
and then redevelop overnight as the trough passes across the
area. Pops increase to high chance overnight into early Sunday
morning and this looks to the best chance of precipitation,
which may linger through mid/late Sunday morning as it moves
east. Dry weather is then expected for the rest of Sunday
afternoon and into Memorial Day.

The models may be overdoing cloud cover both Saturday and Sunday
but it will make for a tricky temperature forecast. Easterly
winds will keep the Lake Michigan shore cooler Saturday but
inland areas may warm well into the mid/upper 70s, possibly even
80 across the west. Though the lake breeze will likely be moving
well inland during the late afternoon/early evening, bringing a
noticeable temp drop. Once the precipitation ends on Sunday,
clouds should scatter out in the afternoon, allowing highs into
the upper 70s/near 80 for most of the area. A lake breeze is
expected to move inland Sunday afternoon, with cooler temps near
the lake. Quite a bit of uncertainty for how warm temps may rise
at the Lake, before the lake breeze, but the highs will likely
be brief. Highs on Monday look to reach the lower/mid 80s for
most of the area, with any lake cooling confined to the Illinois
shore.

Overall pattern later next week into next weekend looks blocky
and likely rather dry with a trough across eastern Canada and
another along the west coast. Tuesday could be another warm day
with temps in the 80s with Wednesday being a transition day to
this pattern with a chance of showers and perhaps a few
thunderstorms, especially across the south, though still quite a
bit of uncertainty. If this pattern does materialize, could be
several days of northeasterly winds and cooler temps near Lake
Michigan.

Not planning any changes to the beach hazard statement for the
Illinois shore tonight. Its possible waves may subside faster
than currently expected but will let later shifts cancel early
if needed. cms

&&

.AVIATION /06Z TAFS THROUGH 12Z SUNDAY/...
Issued at 109 AM CDT Sat May 23 2026

Key aviation forecast messages:

- Arc of -SHRA over southern Lake Michigan will get close to
  MDW/GYY ~6-8Z.

- MVFR CIGS expected through mid morning with a period of IFR
  possible near the lake (~11-15Z)

- Variable wind directions possible during the daytime hours
  before a lake breeze turns winds east again in the afternoon.

An arc of showers has developed over southern Lake Michigan a
bit farther northwest than expected and may briefly reach
MDW/GYY between now and ~8Z. Opted for a VCSH mention at MDW to
account for this given the limited coverage given it has been
struggling to hold together over land so far.

Ceilings have also lowered to MVFR near the lake early this
morning and are expected to gradually lower through the
remainder of the overnight hours from southeast to northwest.
Guidance has trended a bit less pessimistic with time but still
suggest a brief period of IFR CIGs may yet occur toward daybreak
near the lake (ORD/MDW/GYY) with only subtle timing refinement
made with this update. Ceilings then steadily improve mid to
late morning, returning to VFR.

Wind directions will favor an east to northeast direction
the rest of the overnight hours near the lake with light and
variable conditions expected farther inland toward RFD. Light
wind speeds during the morning and early afternoon hours today
leads to lower confidence in directions, which could see a brief
period of variable to northwest winds (<=5kt) before a
reinforcing lake breeze surges inland in the afternoon turning
winds back to the east. Expect further refinement with later
updates.

Our next weather system then approaches the area toward the end
of the 30-hr TAF period. Have held off on a formal precip
mention for now, though a mention of -SHRA may be needed with
later updates.

Petr

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Beach Hazards Statement until 7 AM CDT this morning for ILZ006-
     ILZ103-ILZ104.

IN...None.
LM...None.

&&

$$

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